Joint construction for body shells



A. P. cLAusEN 2,691,538

JOINT CONSTRUCTION FOR BODY SHELLS Oct. l2, 1954 Filed March 3, 1951 mi' fla Illllllnll fa ALBERT P. CLAUSE,

f/ 53 56 32 f2.7o 2! INVENToR.

A TTORNEK Patented Oct. 12, 1954 UNITED STATES PATENT OFFICE JOINT CONSTRUCTION FOR BODY SHELLS Albert P. Clausen, Los Angeles, Calif. Application March 3, 1951, Serial No. 213,727

4 Claims. l

This invention relates to joint structures and refers particularly to junctures between body shells, such as the junctures between cylindrical tank sections.

In some instances where two body shells such as tank sections are to be joined together, it is of utmost importance that the joint not only be structural efficient, but also provide an assembly procedure that may be carried out rapidly without special skill and without need for specialized tools. Certain military situations, for example, call for assembly operations in the eld where tank sections nested together for compactness in transit are shipped to a point of use for quick assembly by personnel on the spot.

Broadly described the present invention meets this requirement for joining body shells together end to end by providing a plurality of radially positioned set screws on one body shell for engagement with a shoulder on metal means extending longitudinally from the other body shell. While such a metal means may take various forms and may be made in one piece to provide the annular shoulder, it is preferably in the form of a plurality of longitudinally positioned studs mounted on a flange or ring inside the circumference of the body shell. The studs may be, and preferably are, formed with conical shoulders for engagement by the set screws so that tightening the set screws creates a cam action to draw the two body shells together in a manner that prevents any looseness or play at the joint.

, An outstanding feature of the invention is the concept of providing the set screws with leadingr surfaces of broken coniiguration for biting into the metal means or studs in such manner as to resist retractive rotation of the set screws.

.The broken conguration provides cutting edges which may, if desired, be designed for greater resistance to retractive rotation than to advancing rotation of the set screws so that the screws may be tightened down with relatively great torque and thereafter require much greater reverse torque for release rotation. Thus theset screws in effect automatically lock themselves against release by biting into the metal means in a manner that discriminates against reverse rotation.

Discrimination against reverse or release rowhenever the set screws tend to retract. Discrimination may be further provided by forming the cuttingv edges to the configuration of curves that are swept back with respect to the direction of inward rotation of the screws. In the lpreferred practice of the invention the desired discrimination is furthered by both of these expedients.

A further feature of the preferred practice of the invention is in the use of set screws with tapered or conical leading ends to impinge against the inclined shoulders provided by the studs, thereby providing more extensive areas of bite than possible with screws having simple flat ends. This combination of a set screw with a conical leading end impinging against a conical shoulder on a longitudinal stud also provides a reverse action that desirably tends to tighten the associated stud as will be explained.

The various features and advantages of the invention will be apparent from the following detailed description taken with the accompanying drawings.

In the drawings, which are to be regarded as merely illustrative,

Figure 1 is a View partly in side elevation and partly in section showing two body shells united by the preferred form of joint construction;

Figure 2 is a transverse section taken on the line 2-2 of Figure l;

Figure 3 is an enlarged sectional detail similar to the sectioned portion of Figure 2 showing a modi'ed form of the joint construction; and

Figure 4 is a face view on an enlarged scale of the leading end of one of the set screws.

In the presently preferred form of the invention exemplied by the drawings, two body shells I0 and II respectively of circular cross-sectional -conguration are adapted to be joined together by set screws I2 carried by the shell II in engagement with longitudinal studs I3 carried by shell Ill.

The studs I3 which are circumferentially mounted on suitable nange means such as inner -radial flanges I4 on the end of the shell I0. In

the particular construction shown in Figures 1 and 2, the inner flanges Id are provided by bracket members I5 that are mounted inside the shell IG' and attached thereto by suitable means such as rivets I6.

As shown in Figure 3,'the plurality of bracket members I5 may, if desired, be replaced by a 1 single ring generally designated Il, which ring has an inner radial ange I8 on which the studs the longitudinal bores.

I3 are mounted. Such a ring I'I has the advantage of reinforcing the shell Ill.

Each stud I3 is formed with a shoulder 20 Vto abut the outer face of the flange III or I8 on which it is mounted and has a shank 2i of reduced diameter that extends through a suitable bore 22 in the flange. The end of the shank 2i of the stud is threaded to receive a suitable nut 23 that abuts against the inner face of the flange. The nut 23 is preferably of the shelf-locking type.

It is essential that the shoulder 2U of each stud I3 face towards the plane of juncture of the two shells ID and II, but the shoulder may be at an angle relative to the plane of juncture.

In the preferred construction shown, each stud I3 had a circumferential channel 25 with divergent sides, thus providing a conical shoulder 26 for engagement with the corresponding set screw I2 with the desired cam actionfor drawing the two shells together.

It is usually necessary to provide-some kind of reinforcement around the end of` the body shell II to provide the desired bore depth for seating the set screws I2. In the construction shown, the body shell II is provided with a ring, generally designated 30, positioned at the end of the shell. The ring 36 has circumferentially spaced openings or longitudinal bores 3I to receive the studs I3 and corresponding radial bores 32 intersecting The radial bores 32are threaded for threaded engagement by the set screws I2.

While the ring 30 may be entirely enclosed by the shell I I, the ring is of the same diameter as the shell in the present construction to serve in effect as an extension of the shell and is cut awair as indicated at 33 to receive the end margin of the shell, the shell being welded to the ring as shown at 34. shown at 35 to provide a seat for the end margin of the shell I I.

Each set screw I2 impinges on the inclined or conical shoulder 26 of the corresponding stud I3 and preferably does so with a cam action tending to tighten the joint between the two body shells. In the preferred construction shown, the leading end of each set screw I2 is beveled to some degree to provide a conical surface 36 to match the depth and inclination of the conical shoulder 2S of the stud.

Thus the leading surface of each set screw I2 includes the conical surface 36 as well as the ilat end surface and at least the conical surface is of broken configuration to provide the desired biting action. It is to be understood that the set screws I2 are harder than the studs I3 and may be tempered or case hardened for this purpose.

In the preferred form of set screw, as best shown in Figure 4, the conical surface 36 is fluted to provide :cutting edges 3l that extend outward to the periphery of the set screw. Preferably, the cutting edges 31 are shaped like ratchet teeth to favor advancing rotation of the set screw, but to resist reverse rotation. In other words, the cutting edges 3l are pointed or inclined towards the direction of reverse or retractive rotation of the set screw so that any such reverse rotation tends to dig the teeth into the metal of the coacting stud I3. Thus, when a set screw is tightened with sufciently great force to cause the set screw to bite into the associated stud, even greater force is required for reverse rotation to loosen the set screw.

It may also be observed in Figure 4 that the teeth 3l conform to curves that are swept back The ring 33 is also cut away as with respect to the direction of advancing rotation of the set screw. The direction of advancing rotation or tightening rotation of the set screw is indicated by the arrow 38.

The previously mentioned reverse action that desirably tends to tighten a stud I3 may be understood by considering Figure 3. Since the set screw I2 has a right hand screw thread, any loosening or release rotation of the set screw is counterclockwise as viewed' from the outer end of the-set screw or as viewed from below in Figure 3. Now, since the cam pressure of the conical nose of the set screw against the conical surface 26 of the corresponding stud I3tends to rotate the stud, just as two meshed beveled gears tend to rotate each other, any loosening rotation of the set screw tends to causev left hand or counterclockwise rotation of the stud as viewed from the end carry ing the nut 23. Thus any rotation transmitted to the stud I3 by release-rotation of the set screw is in the direction to tighten the nut.

It is recognized, of course, that, conversely, tightening of the set screw is in. a direction'` to loosen the stud from the nut, but theinclination of the cutting teeth 3l` is in the rotarydirection to minimize the transmission of motion to the stud in the course of tightening the set screw and in practice no such tendency is evident.

The manner in which the described invention is operated and used may be readily understood from the foregoing description. The bodyshells IIJ and II may be shipped separately to a point of assembly andif, as here indicated, theshells are somewhat conical in configuration, they may be nested for compactness in transit, so that a great number of dismantled body shells may be shipped in a given volume of cargo space. The set screws I2 and the studs I3 together with the nuts-23 will also usually be shipped separately.

At the point of use it isa simple matter toinstall the studs I3 and then move the twobody shells I0 and II together in end to end relationship with the studs I3 extending into the corresponding longitudinal bores 3I in the ring 30. The set screws I2 are then inserted to tighten the joint between the two body shells by cam-'action and finally the set screws are tightened down to cause the cutting edges 31 to bite effectively into the impinging metal of the studs I3.

Thereafter the resistance to reverse rotation of the set screws I2 by virtue of the gouging engagement of the cutting edges 31with the softer metal of the studs effectively prevents reverse rotation of the set screws. I'he bitting engagement of the cutting edges of the set screws with the studs precludes any accidental loosening ofv the-set screws even though the structure be subjected to impacts and excessive vibration overlong periods of time.

The preferred embodimentV of theinvention described in detail herein, by way of example and to illustrate the principles involved, will suggest to those skilled in the art various changes, modications, and other departures from the disclosure that properly lie within the spiritv and: scope ofthe appended claims.

I claim:

1. In a structure of the character described: a first body shell and a second body shell; radial ange means mounted inside said first shell' at the one end thereof; a ring mounted inside said second shell near one endr thereof and adapted to facewsely engage with said flangemeanszwhen the shells are assembled end-to-end, said: ring having circumferentially spaced" openings facing said; ange means; andhaving a: peripheral bore open to the exterior of said second shell and communicating with each of said openings intermediate the ends thereof; a plurality of studs equal in number to said spaced openings spacedly mounted on said flange means to proj ect therefrom in such relationship that a stud extends into and substantially lls each of said openings as said shells are assembled, each stud formed with an annular groove defining at least one annular shoulder inclined to face said flange means; and set screws threaded into said bores for reception in the grooves of the studs, said set screws being of harder material than said studs and having the inner ends :formed with surfaces of broken configuration to bite into said shoulders for anchorage against accidental rotary retraction to thereby hold said studs against separation from said ring whereby said shells are held assembled.

2. A combination as set forth in claim 1 in which said leading surfaces of the set screws are at least in part conical for engaging said inclined shoulder with a cam action to draw the gether, and in which the surfaces of said inner ends are serrated to provide cutting teeth formed to resist rotation of said set screws in the direction of rotary retraction.

4, A combination as set forth in claim 3 in which said studs are secured on said iiange means by means including screw threads and by virtue of contact with the conical shoulders of the studs on the part of the set screws, rotation of the set screws in the direction of retraction tends to rotate said studs in directions to tighten the studs with respect to said screw threads.

References Cited in the iile of this patent UNITED STATES PATENTS- Number Name Date 955,556 Schade Apr. 19, 1910 1,039,058 Hoeiel Sept. 17, 1912 2,300,259 Kueppers Oct. 27, 1942 2,371,801 Chester et al Mar. 20, 1945 2,442,184 Summers May 25, 1948 FOREIGN PATENTS luinber Country Date 203,508 Great Britain Sept. 13, 1923 333,950 Italy Jan.. 17, 1936 516,856 Great Britain Jan. 12, 1940 

